Plug for casings of oil-wells.



No. 679,393. P

A. L. MCPHERSON.

atented July 30, 190|.

PLUG FUR CASINGS 0F GIL WELLS.

(Application led July 80, 190D.) (No Model.)

WTNESSES:

minimal INVENTOR.

ATTORNEY.

UNrrnn Starts Partnr Ottica,

ALEXANDER L. MCPHERSON, OF OAKLAND, CALIFORNIA.

PLUG FOR CASINGS OF OlLmVi/ELLS.

SPECIFICATION forming part of Letters Patent No. 679,393, dated July 30,1901. Application iiled J'uly 30,1900. Serial No. 25,370. (No model.)

T all whom, t may concern:

Be it known that LALEXANDER L. MoPHnR- sON, a citizen of the United States, residing at Oakland, in the county of Alameda and State of California, have invented certain new and useful Improvements in Plugs for Oasings of Oil-Wells, of which the following is a specification.

My invention relates to improvements in plugs for plugging up the casings of oil-wells at the bottom.

In many of the oil-wells in the State of California the strata in which the oil is found are not oil-sands in the strict sense of the term, but are ratherI of the nature of quicksands into which the oil has seeped from a distant source. On this account great difficulty has been experienced by reason of the sand rising up in the bottom of the casing and closing the perforations made in the casing to admit oil from the surrounding strata.

The object of my invention is to provide a plug which when lowered to the bottom of the casing will automatically clamp itself within the casing at the bottom thereof below the perforations for the oil and will thus prevent the sand from rising up in said casing through the open lower end thereof.

In the accompanying drawings, Figure 1 is a longitudinal central section on the line A A of Fig. 3, showing the parts in their relative position when the device is being lowered in the casing. Fig. 2 is a similar view showing the parts when the device is in position at the bottom of the casing. Fig. 3 is a crosssection on the line B B of Fig. 1. Fig. 4 is a cross-section on the line O C of Fig. 2, and Fig. is a longitudinal section of a modified form of the device.

Referring to the drawings, 1 represents the casing of an oil-Well.

2 is the body of the plug, having a central hub-shaped portion 3, radial vertical plates 4, and upper and lower end plates 56. The outer edges of the vertical plates 4 deviate slightly from the perpendicular, as shown in Figs. 1 and 2, the lower ends extending farther from the central axis of the body of the plug than the upper ends thereof, and the upper and lower end plates 5 6 have recesses 7 in vertical alinement with said edges, as shown in Figs. 1 and 2. Said recesses thus form seats or pockets for wedge-shaped keys .8, said keys tapering` toward their lower ends, so as to conform to the shape of said seats. Said keys have on their outer edges ratchet-teeth 9, which point upwardly, so that said keys can readily descend within the casing, since an upward movement of said keys relatively to the body of the plug permits said keys to move inwardly, and thus tends to free the ratchet-teeth from contact with the inner surface of the casing; but if the plug be moved upwardly in the casing then the upwardlypointing ratchet-teeth will engage the inner surface of the casing and oppose the upward movement thereof, being by such ascent forced outward from the body of the plug. I preferably connect the upper ends of said keys by light cords 11 to an eye 12 of a spindle or bolt 13, passing through the central aperture 14 of the body of the plug and having nuts 15 screwed on its lower end, the movement of said bolt relatively to the plug bein glimited bya ring 16, formed on said bolt.

lVhen lowering the plug in the casing, the keys are attached to the plug by means of light wires 17, which are readily broken when the keys are forced outward by the upward movement of the plug-body relative thereto.

The operation of the device is as follows The device is attached to the bottom of the boring-tools and is lowered by the cable into the casing, care being taken that the plug does not descend to a lower level than the bottom of the casing. To insure this, if necessary sand is thrown into the casing, so that the plug may be arrested at a point two or three feet above the bottom of the casing. When the plug has arrived at its lowest point and the cable is drawn upward, the first upward movement of the plug causes the ratchetteeth of the keys 8 to engage the surface of the casing and so push said keys downwardly relatively to the body of the plug, thereby also on account of the wedge-shaped form of said keys moving the keys outwardlyand increasing the friction of the keys against the surface of the casing. This friction is at length increased to such an extent that the cords 11, which attach the keys to the spindle or bolt 13, are broken, as shown in Fig. 2, so that a further upward movement of the 'plug-body tends to wedge said keys still far- IOO ther outward against the surface of the casy ing. The tools are then detached from the eye 12 of the bolt 13 and are drawn up, leaving the plug iirmly vsecured in the casing. Upward pressure of the sand against the bottom of the plug will only tend to iX it more .K

said plates having recesses alining vertically firmly in position.

An important advantage is derived by making the body of the plug of the form shownthat is to say, of upper and lower plates connected by a hub and radial plates. The effeet of this is tp form a double closure against p the sand, for if any sand passes between the edge of the lower plate and the surface of the casing it will then have to ll the space between the two plates before being forced through the interstice between the edge of the upper plate and the surface of the casing.

In the form of the invention shown in Fig. t

5 the cords 1l are dispensed with, and the plug is dropped freely to the bottom of the casing unattached to any cable. In bothi cases, however, the casngs are first fastened in position by the light wires around said S- hand in the presence of two subscribing witf nesses.

keys and the plug-body.

From the outer or free edges of the vertical plates 4 extend pins 18 into grooves 19 in the inner sides of the keys 8. The grooves 19 are so located in said keys with reference to said pins as to prevent the keys from pulling up out of the plugs when the device is being lowered.

I claim- 1. In plugs for casings of oil-wells, the combination of the plug-body having upper and lower plates fitting snugly within the casing,

with each other to form a downwardly-contracted seat, and the wedge-shaped key in said seat having ratchet-teeth on the outer edge of the key to engage the inner surface of the casing, substantially as described.

2. ln plugs for casings of oil-wells, the combination of a plug-body comprising upper and lower plates fitting snugly within the casing, and vertical radial plates between said upper and lower plates, said upper and lower plates being recessed in line with the edges of the vertical plates to form seats for keys, and

. wedge-like keys in said seats, said keys having on their outer edges ratchet-teeth engaging the inner surface of the casing, substantially as described.

In witness whereof l have hereunto set my A. L. MCPHERSON.

Witnesses:

FRANCIS M. WRIGHT, Z. A. DANIELS. 

